Ribbon reverse mechanism for listing calculators



Dec. 6, 1955 H. .1. DUKE 2,725,969

RIBBON REVERSE MECHANISM FOR LISTING CALCULATORS Filed Jan. 29, 1953 2 Sheets-Sheet 1 FIG.

INVENTOR HARVIE J. DUKE AGENT H. J. DUKE Dec. 6, 1955 RIBBON REVERSE MECHANISM FOR LISTING CALCULATORS 2 Sheets-Sheet 2 Filed Jan. 29, 1953 FIGS AGENT United States Patent RIBBON REVERSE MECHANISM FOR LISTING CALCULATORS Harvie J. Duke, Butler, N. 1., assignor to Monroe Calculating Machine Company, Orange, N. 1., a corporation of Delaware Application January 29, 1953, Serial No. 333,871

8 Claims. (Cl. 197-160) The invention relates to type ribbon reverse mechanism and more particularly to improved means for automatically effecting a reversal of the ribbon feed in a positive manner and without increasing tension on the type ribbon during the reversing operation.

Power means operable through yieldable toggle devices for reversing the type ribbon feed which means utilizes clips fastened near the ends of the ribbons either to engage the toggle means as the ribbon is being advanced or to contact a fixed stop to prevent movement of the ribbon and, in either case, cause the toggle device to be thrown to opposite setting and so reverse the ribbon feed, are well known in the art. In both of these arrangements, however, reversal is effected through the ribbon and it has been found that due to the loose manner in which the ribbon is wound upon the spool a plurality of operations of the ribbon advancing means may occur before enough tension is built up in the ribbon to effect an operation of the toggle reversing means. A number of printing operations, therefore, are caused to occur with the ribbon in one position. This impairs the legibility of the printed values and also causes the type bars to cut through the ribbon.

Friction drag means applied to the ribbon spools for obtaining a more tightly wound ribbon and so cause a more prompt operation of the reversing means have proven undesirable since the added tension on the ribbon, among other objections, prevents a proper operation of the well known devices for raising the ribbon to effect a printing in different colors, with vthe result that printing may occur in two colors.

Followers adapted for sensing the decreasing diameter of the ribbon wound on the spool and which when the ribbon has played out sufficiently are caused to be kicked by cyclically driven power means to throw the reverse means are also known to the art, but such means frequently receive several false kicks before sufiicient bite is obtained to throw the reverse means.

Applicant provides novel and simple means for obviating the above objections and effecting a positive operation of the reversing mechanism in such manner that no tension is transmitted to the type ribbon in the reversing operation.

In the drawings,

Fig. 1 is a front elevation of the invention with parts set to feed the type ribbon toward the right;

Fig. 2 is a plan view of the same with certain parts broken away;

Fig. 3 is a detail view of the ribbon feed;

Fig. 4 is a detail view showing the ribbon reverse toggle set to feed the type ribbon toward the left; and

Fig. 5 is a detail perspective view of the means for causing a reversal of the type ribbon feed from a leftward movement to a rightward movement.

The-ribbon feed mechanism is of the type such as used in the well known Monroe Listing Calculator disclosed power operating means for 2,725,969 Patented Dec. 6, 1955 ICC 2 4 in U. S. Patent No. 1,945,027, issued January 30, 1934, to Loring P. Crosman and entitled Listing Calculator, to which reference is made for details of structure and operation not forming a part of the present invention.

The usual ribbon spools 1 and 2 are supported upon and rotate with their respective spindles 3 and 4, pivotally mounted upon brackets 5 and 6 secured by studs 17 to the rear casing of the machine. Fastened to spindles 3 and 4 are ratchet wheels 7 and 8. The wheel 7 is adapted for engagement by a suitable feed pawl 9 for rotating spindle 3 counterclockwise to advance the type ribbon 10 toward the left, while wheel 8 is adapted for engagement by a similar pawl 11 for clockwise rotation to feed the ribbon toward the right, all as hereinafter described.

Pawls 9 and 11 are pivotally secured by means of studs 12 and 13 to suitable lugs 14 and 15 formed at the left and right end respectively of a slide member 16 which is supported to the rear casing of the machine by means of studs 17 and the brackets 5-6.

Fulcrumed at 18 to the slide 16 is a toggle link 19 pivotally connected at 20 to a link 21 and biased by a suitable toggle spring 31, the other end of which is secured to link 21. The rightward end of link 21 is pivotally connected at 22 to one arm of a bell crank lever 23 pivotally supported at 24 upon bracket 6 and provided with an arm 25 embraced by the bifurcated end of a lever 26 (Fig. 3) pivotally mounted at 27 to bracket 6. A power operated shaft 28 adapted for reciprocatory movement during each machine cycle of operation, as described in reference Patent 1,925,047, has fastened thereto an arm 29 provided with a stud 30 adapted during a forward or counterclockwise operation of arm 29 to impart clockwise movement to the lever 26. Clockwise movement of lever 26 acting through arm 25 imparts a clockwise movement (Fig. l) to bell crank lever 23 and thereby moves link 21 toward the left. With toggle 19 in a counterclockwise setting, as illustrated in Fig. 1, a leftward movement of link 21 will effect movement of slide 16 from its extreme right hand position A to the intermediate position shown in Fig. 1 and as indicated by the arrow being opposite the letter B.

During a return movement of the arm 29, the stud 30 restores lever 26 and bell crank 23 returns link 21 toward the right, whereupon said link acting through link 19 and toggle spring 31 will return slide 16 to the position indicated by the letter A.

In the above described excursion of slide 16, pawl 9 will not be carried to the left a suflicient distance for the pawl to contact ratchet wheel 7, and therefore no movement is effected thereby to the type ribbon at this time. Pawl 11, however, in the return movement of slide 16 at this time engages the teeth of ratchet wheel 8 and imparts a clockwise rotation to spool 2 for efiecting a rightward movement of the type ribbon 10.

If, on the other hand, toggle 19 is in a clockwise setting, as illustrated in Fig. 4, slide 16 will normally be in the intermediate position B and upon operation of hell crank 23 by arm 29 and lever 26, link 21 in moving toward the left then acts through link 19 and toggle spring 31 to move slide 16 from the position B to its extreme left hand position as indicated by the letter C, and is then subsequently returned to the intermediate position B.

During this excursion of slide 16, pawl 9 is now carried leftward a sufiicient'distance to engage ratchet wheel 7 and rotate said wheel counterclockwise to impart a leftward movement to the type ribbon 10. In this operation pawl 11 is merely carried to the left and returned idly from and to the position illustrated in Fig. 2.

To prevent pawls 9 and 11 from imparting a reverse rotation to the ratchet wheel 7 or 8 in the return movement of said pawls from an active stroke, the usual spring tension holding pawls 32 and 33 are provided,

pivotally mounted upon the fixed brackets and 6 respectively.

Positive reversing means In order to simplify the description, means are described only for effecting a reversal of the ribbon feed from a leftward movement to a rightward movement. It is understood, however, that similar mechanism operating in like manner also provides for reversing the ribbon feed from right to left.

The pivot stud 13 for the pawl 11 in the described movement of slide 16 from the position B of Fig. 2 to the position C is adapted to engage a cam edge 34 formed on the forward edge of the holding pawl 33 and rock the pawl 33 in a clockwise direction out of engagement with ratchet wheel 8, so that said wheel will be free to rotate as wheel 7 imparts a leftward movement to the type ribbon 10.

As shown in Fig. 5 a portion of the hub 35 of spool 2 has been cut away to provide a recess 36 therein and a pointed tooth 37 has also been formed in the hub 35 upon which one end of the type ribbon may be impaled to rotate with spool 2.

A slide 38 mounted for movement on the rear casing of the machine by means of slot connection 39 is urged toward the right by means of a light spring 41 and is provided with an arm 42 adapted to engage the diameter formed by ribbon 10 in the winding of said ribbon upon spool 2. As ribbon 19 is unwound from spool 2, spring 41 moves slide 38 rightward and arm :32 will sense the diminishing diameter of type ribbon 10 until the ribbon is substantially completely unwound from the spool 2, and the spool has been rotated sufiiciently to bring the recess 36 therein opposite the arm 42 of slide 38. The following means are provided, however, so that at this time slide 38 will be prevented from making a further rightward movement into engagement with the recess 36. The rear edge of pawl 33 is provided with a shoulder portion 43, the left edge of which is adapted when pawl 33 is rocked clockwise by pin 13 in the leftward feeding stroke of ribbon 19 to be moved into the path of movement of a downwardly projecting extension 45 of the slide 38 and thereby block any rightward movement of said slide at the time recess 36 is being rotated to its position opposite arm 42. Near the end of the return stroke of slide 16, pin 13 releases pawl 33 for a clockwise movement by the spring 46, connected between the pawls 11 and 33 as shown, and

thereby disengages shoulder 43 of pawl 33 from projection 45 of slide 38. Upon release of pawl 33 from slide 38, said slide under influence of spring 41 is now moved a further distance toward the right, in which arm 42 enters the recess portion 36 of hub 35. In the above movement of slide 38 projection 45 is carried to a position in the rear of shoulder 43 of pawl 33 so that upon a subsequent operation of the ribbon feed mechanism, pawl 33 will be held against clockwise rotation and pin 13, engaging the cam edge 34 of said pawl, will hold slide 16 against any leftward movement. Slide 16 being thus held a full leftward movement of link 21 will be effective during said operation to assure of toggle link 19 being rocked clockwise in a positive manner about fulcrum point 18 to the position shown in Fig. 1. In the return movement of arm 29, link 21 then moves slide 16 toward the right from position B to position A, during which pawl 11 engages ratchet wheel 8 and rotates spool 2 clockwise to impart a rightward movement to the type ribbon 10. During the rightward movement of slide 16, pin 13 releases pawl 33 and said pawl is caused to be rocked counterclockwise by spring '46 to reengage ratchet wheel 8 and to restore shoulder 43 out of the path of movement of the projection 45 of slide 38.

Due to the increased diameter of the ribbon 10 on the driving. spool and the reduced diameter of said ribbon on the trailing spool at the time of a reversal, a single tooth of movement of the driving ratchet is ample to rotate the trailing spool sufiiciently to bring the recess 36 into cooperative position with arm 42 of slide 38. It has been found in practice, however, that in general a movement slightly in excess of three teeth is best suited.

It will be noted that during a final turn of the trailing spool said spool acts to prevent the slide 38 from moving to the rear of the shoulder 43 of pawl 33 and that the pin 13 acts promptly on pawl 33 so that said pawl is moved into position early enough in the final feeding operation to block slide 38 before recess 36 is rotated into cooperation therewith.

It has been found that by placing the arm 42 so as to contact the type ribbon 10 near the lower portion thereof that as the ribbon is wound around the spool said arm also serves as an iron to smooth out any wrinkling that might otherwise occur in the ribbon as it is being advanced immediately following a reversing operation at a time when the ribbon is in raised position for a color change, 1

Light friction springs 44 passing around the spindles 3-4 serve to hold slack out of the type ribbon and also act, in centralizing from their displaced condition due to the rotative friction action of spindles 3 and 4, to take up any slack which would otherwise occur as the type ribbon is restored from the displaced position shown in Fig. l to its normal lower horizontal position.

Having now described novel means and the manner of use whereby ribbon feed devices may be automatically reversed in a positive manner and without adding tension to the type ribbon in the reversing operation, what I claim is:

l. Ribbon reverse mechanism for listing calculators or the like comprising the combination of a type ribbon, storage spools for said ribbon including hubs having a recessed portion, ribbon feed devices including an actuator cooperable with one of said spools to advance the ribbon in one direction and with the other of said spools for advancing the type ribbon in an opposite direction, an operating train for said actuator including a toggle member in said operating train settable in one position for restraining operation of said actuator to a selective path of movement adapted for advancing the type ribbon in a given direction and in another set position for restraining operation of said actuator in an extension of said path of movement to advance the type ribbon in an opposite direction, yieldable sensing means for the type ribbon adapted to determine when the ribbon is substantially completely unwound from the storage spool, blocking means for the sensing means operable by said actuator to preventa further movement of the sensing means when the type ribbon is substantially completely unwound from the spool and said recessed portion is rotated opposite said sensing means, and wherein subsequent release of said blocking means permits further movement of the sensing means, and a blocking means controlled by the sensing means during said further movement to prevent a subsequent operation of the said actuator and thereby cause the said operating train to adjust the toggle member to a reverse setting and thereby limit susbequent operations of said actuator within said extension of said path of movement wherein operation of the feed devices thereafter will impart movement to the type ribbon in an opposite direction.

2. The invention in accordance with claim 1 and wherein the said actuator includes a yieldable feed pawl related to each of the said ribbon spools and adapted to selectively impart a movement to the type ribbon in accordance with the setting of said toggle member, and wherein said feed pawls are caused to remain stationary cur in an adjustment of said toggle member during the reversing operation control for said ribbon.

3. The invention according to claim 2 wherein said first named blocking means includes a pivoted pawl adapted also to prevent a reverse rotation of the ribbon spool during a return movement of the ribbon feed devices from an active stroke.

4. The invention according to claim 3 wherein the sensing means includes a spring urged slide having a projection adapted in the said further movement of said slide to be brought to position for preventing a movement of said first named blocking means and wherein said blocking means is provided with a shoulder portion adapted when the blocking means is thus held against operation to also prevent a feeding operation of the ribbon feed devices and thereby cause said devices to be set to effect a reverse operation of the ribbon feed.

5. The invention according to claim 4 wherein the sensing means is provided with a cam surface adapted for cooperation with the recessed portion of the ribbon storage spool to restore said slide during a reverse operation of the ribbon spool.

6. The invention according to claim 1 wherein the first named blocking means includes a pivoted pawl related to each of said spools and having a shouldered portion thereof adjusted by said actuator in an active ribbon feeding stroke movement to prevent a movement of the sensing means into said recessed hub of the trailing spool as the type ribbon is being substantially completely unwound from said spool, and wherein the said pawl re lated to the trailing spool thereafter is caused to be released during an inactive return movement of said actuator to release the sensing means for movement into said recess, and means positioned by the sensing means during said movement thereof to disable said pawl and the said actuator against a subsequent operation of the ribbon feed operating train, and wherein said operation of said train is thereupon caused to adjust the toggle member to an opposite setting whereby operation of the feed devices thereafter will advance the type ribbon in a reverse direction.

7. The invention according to claim 6 and wherein said blocking pawls are adapted for engagement with a ratchet wheel of the related ribbon spool to prevent a reverse operation of said spools in a return stroke of said actuator, and wherein said actuator is adapted during a feeding stroke movement to disengage the blocking pawl related to a trailing spool and to move idly relative to the pawl related to the driving spool in either path of movement of said actuator.

8. Ribbon reverse mechanism for listing calculators or the like comprising the combination of a type ribbon, a plurality of storage spools for said ribbon having hubs with a recessed portion, ribbon feed devices including an actuator cooperable with one of said spools to advance the ribbon in one direction and with the other of said spools for advancing the ribbon in an opposite direction, an operating train for said actuator including a toggle device in said operating train settable in one position to eifect reciprocatory operation of said actuator in a linear path of movement adapted to advance the type ribbon in one direction and in another set position for effecting operation of said actuator in an adjacent path of movement forming a linear extension of said first path of movement to advance the type ribbon in an opposite direction, yieldable sensing means including a spring urged slide related to each of said spools and adapted for movement into said recessed hub of the related ribbon spool after the type ribbon is substantially completely unwound therefrom, blocking means for each of said slides including related pivoted pawls having a shouldered portion cooperable with the sensing slide of the trailing ribbon spool in a final feeding operation of the actuator to block said later movement of said related slide, and wherein said pawls are provided with a cam surface cooperable with said actuator in said final feeding operation to bring the said shoulder of the pawl When related to the trailing spool into blocking position, and whereby a subsequent release of said pawl by said actuator permits a movement of said slide into said recess and thereby position said slide so as to block a subsequent operation of said pawl, and whereby the said cam surface of said pawl thereupon acts to prevent an operation of said actuator and cause said operating means to adjust the said toggle means for controlling operation of said actuator in a different path of movement and reverse the direction of the ribbon feed.

Wetmore et a1. May 5, 1908 Kettering et al. Apr. 27, 1915 

